1913] COOPER—ISLE ROYALE 225 
opment of the burn forest is exceedingly rapid, thanks to the 
prolific sprouting of the birch, but the transition from burn forest 
to climax seems to be a slower process. Occasional areas of climax 
forest in which the birch element is mainly composed of groups of 
immense stump sprouts probably represent the penultimate stage in 
a burn succession following some prehistoric fire. 
The effect of fire upon the composition of the flora is shown in 
table VI. The statistics were obtained from a study of areas of 
equal size in the unburned and burned portions of Smithwick 
Fic. 54.—A young burned forest composed mainly of birches in clumps: the 
lower aie th i is J oth communis var. depressa, Pleris aquilina, and other species; 
near Park Place Hot 
Island. The fire occurred about 1 5 years ago. The points to be 
noted are the destruction of the conifers and a part of the herbace- 
ous flora, the increase of Betula and another portion of the her- 
baceous vegetation, and the appearance of Populus, Rubus, and the 
fireweeds. 
2. Humus destroyed; bare rock exposed.—In such cases the 
reestablishment of the climax follows closely along the line of the 
rock shore succession, through lichen and crevice plant, and heath 
mat stages. Such differences as occur are due to the more thorough 
disintegration of the rock with greater abundance of soil materials 
